A method is described for the identification and/or localization of objects where at least one transponder provided on the respective object is excited to emit transponder data stored in the transponder which characterize the respective object and where the transponder data emitted are detected. The invention is further directed to an apparatus for the performance of this method.
Transponders used in corresponding methods and apparatuses are also termed RFID transponders (radio frequency identification transponders) as, conventionally, a large coil and a capacitance are present in the transponder, with the coil being excited by a high-frequency magnetic field which is transmitted via a coil of an RFID reading device forming an antenna. In this way, a voltage is generated in the coil of the transponder which acts as the power supply for the transponder.
The transponder conventionally contains a microprocessor which is supplied with power in this way and which emits transponder data stored in the transponder by controlling the current in the coil of the transponder by means of a corresponding magnetic field. This modified magnetic field effects a change in the current or the voltage in the coil of the reading device so that the transponder data emitted are detected by the reading device.
The use of such transponders provides a number of advantages. On the one hand, a relatively large amount of data can be stored in a transponder so that the corresponding information content is very high. In addition, not only read-only transponders exist, but also rewritable transponders so that, if necessary, the data contained can also be modified or added to. Another advantage is that the optical path between the reading device and the object does not need to be unobstructed as reading is performed by inductive coupling and that, for the same reason, a corresponding apparatus is not sensitive to dirt.
However, in addition to these advantages, the following disadvantages also exist. It is particularly problematic that an exact localization of a transponder is not possible. This is a problem when objects are to be recognized which follow very closely on one another. When several objects are simultaneously located in the reading field of a reading device, a clear localization of a transponder and thus of the object carrying the transponder is not possible.
Another disadvantage is that reading is frequently not possible if the transponder is located in the vicinity of metallic objects such as an aluminum case. Another problem is the still relatively low popularization due to the low degree of standardization.
It is an object of the invention to provide a method and an apparatus of the kind first given in such a way that an exact localization and a clear identification of an object is also possible in the above-mentioned problematic cases.
This object is satisfied in accordance with the invention starting from a method of the kind first given by the object additionally being scanned by at least one optical sensor and by the object being identified and its location determined from a combination of optical data detected by the optical sensor and the detected transponder data.
An apparatus formed in accordance with the invention comprises an electromagnetic sensor unit, with which at least one transponder provided on the respective object can be excited to emit transponder data stored in the transponder which characterize the respective object and with which the transponder data emitted can be detected, with an optical sensor to scan the object and an analysis unit to clearly identify the object and/or to determine the location of the object from a combination of optical data detectable by the optical sensor and the emitted transponder data which can be detected being additionally provided.
By means of the combination of an RFID system with an optical scanning unit, the advantages of the two different systems are optimally combined with one another. Optical scanning units have the advantage that an exact localization is possible. The disadvantages of optical scanning systems, namely of relatively low information content, sensitiveness to dirt and the need for an optically unobstructed path between the sensor and the object, are compensated for by the corresponding properties of the transponder system. Both a clear identification and a clear localization of an object provided with a corresponding transponder is thus possible by means of the combination in accordance with the invention of an optical scanning unit and an RFID system.
In accordance with an advantageous embodiment of the invention, the localization is performed by an analysis of the optical data and/or the identification of the object by analyzing the transponder data. As an exact determination of the location of the object is possible by means of the optical detection unit if two or more objects, for example, are detected within a reading field by the reading device of the transponder, the location of the objects can be determined by means of the optical analysis unit by an analysis of the optical data of the respective object. It is also possible, as is described in more detail below, to achieve both a clear identification and a clear determination of the location of the object even with an incomplete recognition of the optical and/or transponder data by means of an analysis of a corresponding combination of these data.
In accordance with a preferred embodiment of the invention, a barcode arranged on the object is detected and decoded by the optical sensor, with the object being identified and/or its location determined from the decoded barcode data together with the transponder data. The use of barcodes arranged on the object allows, on the one hand, a reasonably priced and globally standardized method of optical scanning, with the coordinates of the barcode read being able to be determined very precisely in space by means of conventional barcode scanning units. As the maximum information content of barcodes is relatively low and comprises, for example, around 30 to 50 characters with one-dimensional scanning, transponder data with a substantially larger information content stored in the transponder can, if required, be received and analyzed.
A method in accordance with the invention can further be advantageously characterized by at least a part of the data stored in the transponder corresponding to the data encoded in the barcode, by the transponder data detected being compared to the corresponding decoded barcode data, by an agreement between the recognized partial barcode data and the detected transponder data being sought in the event of incompletely recognized barcode data and, if such agreement is found accordingly, by the object being identified by the transponder data and its location being determined as the location of the partially decoded barcode.
In this way, it is possible that both a clear identification and an exact localization of the object are possible even with an incomplete detection of the barcode present on the object. If, for example, multiple transponders are detected within the reading area, the object identification data contained in the transponder data are compared to the identification data detected by means of the barcode. In the case of an incomplete detection of the barcode data, for example due to dirt on or a partial covering of the barcode, agreement is sought between the recognized partial barcode data and the detected transponder data and, in the event of such agreement being accordingly found, the object is identified in accordance with the transponder data. The location can be determined using the partially recognized barcode location which can be determined exactly by means of the barcode detection unit.
In accordance with another advantageous embodiment, the reading reliability can be substantially increased by the combination in accordance with the invention, as the information used for the identification is encoded and read out in two different ways with different physical principles. In accordance with the invention, this is advantageously performed by at least a part of the data stored in the transponder corresponding to the data encoded in the barcode, by the transponder data detected being compared to the correspondingly decoded barcode data, and by the object only being deemed to be successfully identified in accordance with the data in the case of a corresponding agreement between the transponder data and the barcode data. In this way, the system is provided with a redundancy which has a very small error liability due to the different physical properties of the transport paths.
In accordance with another advantageous embodiment of the invention, the optical reflectance profile of the object is determined by the optical sensor, the reflectance profile determined is examined for values typical for the optical design of the transponder for the optical detection of the location of the transponder, and, if the transponder is recognized, the localization of the object is performed by an analysis of the recognized location of the transponder and the identification of the object by the analysis of the transponder data detected.
Thus, instead of a barcode, the optical reflectance profile of the object can also be detected and analyzed by an optical detection unit. For the recognition of the transponder, the detected reflectance profile of the object can be examined, in particular, for unmistakable areas of given optical properties, for example, color, brightness, shape or the like, with, if one single corresponding area is recognized on the object, this area being identified as the transponder. The location of the transponder in space can, in turn, be precisely determined by this optical analysis so that an exact association can be made between the transponder location and the transponder data identifying the object.
In accordance with another advantageous embodiment of the invention, the optical reflectance profile of the scanned object is determined by the optical sensor, the reflectance profile determined is compared to a reflectance profile of the object bearing the transponder determined from the transponder data detected and stored in the transponder, and, in the event of sufficient agreement between the reflectance profiles, the scanned object identified by the transponder data detected.
If objects following on from one another have clearly distinguishable reflectance profiles, a clear identification of the respective object by means of the reflectance profile detected is possible in the manner described by the storing of said reflectance profiles in the transponder provided on the respective object. In turn, an exact determination of the location of the respective object is possible using the optical detection so that a clear association of the transponder with the object is also possible in this way and thus a determination of the location of the object is achieved.
It is furthermore also possible that geometrical data of the object, for example the contour and/or the length and/or the width and/or the height of the scanned object, are determined by the optical sensor, that the geometrical data determined are compared to corresponding geometrical data of the object bearing the transponder determined from the transponder data detected and stored in the transponder, and that, in the event of sufficient agreement between the geometrical data, the scanned object is identified by the transponder data detected. Analogous to the analysis of the reflectance profile, it is thus possible to perform a clear association of the respective transponder with the respective object using the geometrical data stored in the transponder and a comparison to correspondingly detected geometrical data of objects following on from one another having clearly distinguishable geometrical data. An unmistakable identification and localization of the objects detected is thus also possible in this way.
The detection of a barcode, the geometrical data and the reflectance profile can be performed singly in each case or also in any combinations thereof. Using laser scanners of current designs, the barcode, geometrical data and the reflectance profile can, for example, be detected simultaneously, whereby increased redundancy and/or an improvement in the reliability of the results is achieved.